E-Flora BC: Electronic Atlas of the Flora of British Columbia

Sium suave Walter
hemlock water-parsnip (hemlock waterparsnip)

Introduction to Vascular Plants

© Allan Carson  Email the photographer   (Photo ID #68952)

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Distribution of Sium suave
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Species Information

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Terrestrial to semi-aquatic perennial herb from a very short, erect stem-base (not chambered) with fibrous roots that sometimes are tuberous-thickened; stems solitary, 0.5-1.2 m tall, stout, hollow, strongly ridged, generally branched above.
Stem leaves pinnately compound; leaf stalks with sheathing bases, blades 2-9 cm long, 1.5-10 (20) mm wide, divided into 7-15 leaflets that are lance-shaped to linear and toothed; submerged leaves much more finely divided; primary lateral veins of the leaflets not directed towards the base of the teeth.
Inflorescence of compound umbels; flowers white, small; calyx teeth minute or obsolete; involucel bractlets 6-10, narrow, reflexed.
Oval to elliptic, 2-3 mm long, prominently ribbed.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Wet streamsides, swamps, marshes, lake and pond shores in the lowland and montane zones; common throughout BC except Queen Charlotte Islands and adjacent coast; N to AK, YT and NT, E to NF and S to FL, VA, KS and CA.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Sium suave

The table below shows the species-specific information calculated from
original data (BEC database) provided by the BC Ministry of Forests and Range.
(Updated August, 2013)

Site Information
Value / Class




Elevation (metres) 0 753 1310
Slope Gradient (%) 0 0 18
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
58 226 290
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
5 7 8
Modal Nutrient Regime
Number of field plots
 species was recorded in:
Modal BEC Zone Class
All BEC Zones (# of stations/zone) species was recorded in: BG(7), BWBS(7), CWH(9), ICH(15), IDF(59), MS(1), PP(1), SBPS(9), SBS(29)


The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is not evaluated, unknown or variable.

Synonyms and Alternate Names

Sium cicutifolium Schrank
Sium floridanum Small
Sium suave var. floridanum (Small) C.F. Reed

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References